.. Well, for example, right now I'm training my foot speed. So I do two sessions a week to improve this, and two other sessions I do are 'maintenance routines', which involves training all the other aspects of my game, just vaguely, to keep my skills sharp. Do I need these type of sessions to stop myself from going 'rusty', or are most skills like riding a bike, and will stay with me.

They certainly can't hurt you. If you feel you desperately need the time to work on something else, or rest, then do so, but I think it's good to do some 'mainteance' or other basic stuff you already have a handle on to both keep your skills sharp and give you a little break from the frustration of learning new stuff all the time, or working out.

All roads lead to Rome.

Triskaidekaphobia: The unnatural fear of the number 13.Most of Ballack's opposition have this phobia.